Not only that, nearly all of them use the IMX377 :)

That said, there is TREMENDOUS variance in image quality, even if you're using the same sensor. The ISP and color tuning process is extraordinarily complex and severely subjective; the noise filtering and encoding processes are incredibly difficult as well.

And then there is Autofocus; HDR blending; when to do HDR at all; video stabilization; and so on and so on.